What is the value of S and W 659?

Trying to put a value on anything with just the limited information provided is hard to do. Value depends on a combination of many factors. You have only providided the most generic description. Without a detailed description to include, finish, barrel length, grip material, sights, box, origiinal paperwork and any accessories, only a general estimate can be given. This weapon could be in the 100-500 USD price range more or less.